CHANGE YOUR UNIVERSE S o i l - C e m e n t f o r B u i l d i n g F o u n d a t i o n s

Transcription

1 CHANGE YOUR UNIVERSE S o i l - C e m e n t f o r B u i l d i n g F o u n d a t i o n s Doug Hula, P.E. Gosling Czubak Engineering Sciences, Inc.

2 Presentation Outline Introduction Overview Case Study Inspection & Testing Advantages Applications Closing/Questions + =

3 What is Soil-Cement? Highly-compacted mixture of soil, cement and water Distributes load over broad areas Sometimes called cement-stabilized soil

4 Where is Soil-Cement Used? Method of subgrade improvement Successfully used for roadbuilding in Michigan Rarely (if ever) used for structure foundations in Michigan

5 Case Study St. Marys Cement o Charlevoix Upgrade Project Long-term professional relationship o Geotechnical engineering and materials testing since 1970 s o Environmental services o Surveying

6 Case Study

7 Case Study Industrial Plant Upgrade o Required large foundation bearing capacity beneath multiple large structures Blend Silo Coal Mill Building Raw Mill Cyclone Finish Mill Building A variety of other smaller structures

8 Case Study Existing Site Conditions o Extensive geotechnical exploration o Highly variable depth to bedrock o Variety of old fill gravel, sand, silt & clay + cobbles & boulders Piles considered for foundation o Soil-cement as alternative o Change the Universe

9 Case Study Soil-cement allowed subgrade soil bearing pressure to be increased from 3,000 psf to 8,000 psf The first component to be constructed was the blend silo 79 feet in diameter 225 feet tall February in Northern Michigan What could possibly go wrong?

10 Mix Design and Trial Batching Develop mix design to achieve 0.8 MPa (116 psi) Samples of material o Cement o Soil (sand) Variables o Amount of cement o Moisture content o Compactive effort

11 Trial Batching Mix ID Specimen % Moisture % Cement Diameter (in) Height (in) wt (gm) 1 A B A B A B A A

12 lbs/ft^3 (wet Density) Trial Batching Proctor Values at 6% Cement Moisture Percentage

13 Trial Batching

14 Compresive Strength PSI Compresive Strength PSI Trial Batching Compressive Strength vs. Cement content (8.5% moisture) 4.66 MPA Compressive Strength vs. Cement content (10% moisture) 4.55 MPA MPA 570 PSI 4.20 MPA Cement Content - % of Batch Weight MPA 550 PSI 8 10 Cement Content (%)

15 Trial Batching Conclusions o Every combination of variables in the lab produced results that met and exceeded the minimum required design strength o 6% cement content at 8.5% moisture was recommended Most economical mix Adequate strength to ensure successful construction

16 Pre-Construction Methods Considered o Batch and mix in excavation o Use of a pug mill o Batch and mix materials nearby, then place and compact in the excavation Better control Consistent layers Cost-conscious vs. pug mill

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19 Mixing Excavator Bucket Method o Slow process; not enough mixing happening

20 Mixing Front End Loader Method o Now we re making progress!

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23 Placement Soil-cement was placed in 12 layers & compacted o Density testing and sample collection for compressive strength

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25 Insulated blankets protected material from freezing o Average overnight temperature of 19 F Placement

26 Placement The next day, it was as hard as concrete (almost!) 1 MPa = 145 psi 145 psi 3000 psi

27 Results Average actual strength at 7 days was 930 psi o Well above minimum strength o Low 240 psi (200% of design), High 1425 psi [We were never really worried]

28 Results The entire soilcement foundation was placed in 12 days o Excellent working surface for placing forms and reinforcing steel

29 Blend Silo Concrete foundation complete, starting walls o /8 diameter, /8 high walls o Placed using continuous slipform method

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31 Continuous Slip Form

32 Continuous Slip Form

33 Blend Silo Soil-cement foundation did not move under the weight of the silo Settlement monitoring will continue as the silo is loaded with material

34 Other Structures Raw Mill Cyclone Building 3,900 sf Coal Mill Building 8,700 sf Finish Mill Building 16,900 sf Clinker Cooler (Partial) 2,500 sf o All have heavy equipment and dynamic loads

35 Raw Mill Cyclone Building

36 Raw Mill Cyclone Building

37 Raw Mill Cyclone Building

38 Coal Mill Building

39 Coal Mill Building

40 Finish Mill Building

41 Finish Mill Building

42 Inspection & Testing Monitoring to ensure proper proportions and moisture content Adequate mixing Layer thickness and compaction Compressive strength Protection of placed and cured material

43 Advantages Speed of design and construction Frost-proof material eliminates minimum footing depth for frost heave Cost savings compared to deep foundation options o Piles, caissons, etc. o Soil-cement costs range from $42 to $110 per cubic yard, depending on volume produced per day

44 Deep Foundations

45 Advantages Cost savings vs. deep foundation options Mobilization $25,000 Cost per foot of piles $26/foot Pile load testing $15,000 Pile caps and grade beams

46 Advantages Ease of construction at varying bearing levels Reliability o In-place strength tests each layer vs. pile load tests on selected test piles

47 Applications Industrial projects Commercial projects Education and Healthcare projects Residential projects

48 Applications Transportation projects Existing cement plant projects o Cement component already on site Almost any project with inadequate soil properties to support foundation loads

49 Special Thanks Fabio Cittadin, Votorantim Cimentos North America (VCNA) Cortney Schmidt, St. Marys Cement Milton Martins de Matos, Eng Civil, MSc, PhD MDC Charlevoix, Michigan Rieth-Riley Charlevoix, Michigan

50 Questions

51 For More Information Geotechnical o Soil & Foundation Engineering, Retaining Walls, Slopes Construction Observation & Inspection Materials Testing Laboratory Testing Environmental, Surveying and other services

52 Contact Information Doug Hula, P.E. Gosling Czubak Engineering Sciences, Inc office cell